1. Field
Example embodiments may relate to a magnetic memory, for example, to a magnetic memory where data bits represented by magnetic domains may be stored in an array using magnetic domain motion.
2. Description of the Related Art
Magnetic random access memories (MRAM) are a type of non-volatile magnetic memory. MRAM is a solid state magnetic memory that uses magnetic resistance due to a spin-dependent conduction characteristic of a nano magnetic material. MRAMs may use giant magnetoresistance (GMR) and/or tunnel magnetoresistance (TMR) because spin, which is a degree of freedom of an electron, may have a significant influence on electron delivery.
GMR is a resistance difference that may be generated by a non-magnetic material between ferromagnetic materials having a same or different magnetization direction as an adjoining arrangement of ferromagnetic material/metallic non-magnetic material/ferromagnetic material. TMR is resistance where a current may more easily flow when two ferromagnetic materials have a same magnetization direction in an adjoining arrangement of ferromagnetic material/insulator/ferromagnetic materials than if the two ferromagnetic materials have different magnetization directions. Because MRAMs using GMR have a relatively smaller resistance difference caused by magnetization direction, a larger voltage difference may not be possible to achieve. Because MRAMs may have a larger cell formed by a metal oxide semiconductor field effect transistor (MOSFET) and GMR layer, it may be desirable to pursue MRAMs using a TMR layer.
An MRAM may include a transistor, which may be a switching device, and/or a magnetic tunnel junction (MTJ) cell in which data may be stored. The MTJ cell may include a pinned ferromagnetic layer with a pinned magnetization direction, a free ferromagnetic layer with a magnetization direction parallel or anti-parallel to the pinned ferromagnetic layer's magnetization direction, and/or a non-magnetic layer between the pinned ferromagnetic layer and the free ferromagnetic layer to magnetically separate ferromagnetic layers.
Because a related-art MRAM may store only one bit of data per MTJ cell, there may be limitations in data storage capacity of MRAMs. A different type of storage technology may be required to increase information storage capacity of magnetic memories such as MRAMs.